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CRANKCASE VENTING ARRANGEMENT FOR REFRIGERATING SYSTEM M 4 3 w j O /M/ L 4 g 5 March 3, 1964 United States Patent 3,123,287 CRANKCASE VENTING ARRANGEMENT FOR REFRIGERATING SYSTEM Emil T. Neubauer, Sidney, Ohio, assignor to Copeiand Refrigeration Corporation, Sidney, Ohio, a corporation of Michigan Filed Dec. 16, 1959, Ser. No. 859,993 6 Claims. (Cl. 2302tl6) This invention relates to refrigerating systems, and more particularly to means for maintaining proper lubrication of compressors in hermetically sealed motor-compressor units.

In refrigerating systems using self-contained motorcompressor units in which the returning refrigerant 1s used to cool the motor it is important that the crankcase pressure be maintained at a sufficiently low level relative to the rest of the system to permit return of lubricant collected in the motor compartment to the crankcase. Dur

ing the starting period of compressor action, refrigerant mixed with the lubricant in the crankcase will foam and the foamed oil will tend to be drawn from the crankcase. Check valve passages provided for permitting pressure relief from the crankcase while preventing loss of lubri cant present additional problems in that the refrigerant being supplied to the intake manifold may back up through such passages to maintain or even increase the crankcase pressure. Piston blowby is another factor making it difficult to maintain crankcase pressure at a sufiiciently low level.

It is an object of the present invention to overcome the disadvantages of previously known means for obtaining crankcase pressure reduction in refrigerating units of this type and to provide a novel and improved construction for venting the crankcase and maintaining lubricant supply in an eilicient and reliable manner.

It is a further object to provide a novel and improved pressure control arrangement of this nature which utilizes the inherent flow characteristics of the system to achieve and maintain proper crankcase pressure.

It is also an object to provide an improved compressor crankcase construction of this type which is of simple, economical and trouble-free construction and which in no way interferes with the functions of other portions of the refrigerating system.

Other objects and features of novelty of the invention will be specifically pointed out or otherwise become apparent when referring, for a better understanding of the invention, to the following description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a partially schematic cross-sectional view in elevation of a compressor crankcase with portions of the adjacent motor compartment and cylinders, showing the novel system of this invention;

FIGURE 1A is an enlarged fragmentary view of a portion of the gas equalizing check valve showing the bypass therethrough; and

FIGURE 2 is -a partial top plan view showing the crossscctional configuration of the eduction passage.

In general terms, the invention comprises a pair of check valve passages, one connecting a compressor crankcase to the adjacent motor compartment below the oil level and the other connecting the crankcase space above the oil level with the gas flow passage leading from the motor compartment to the intake manifold, together with means in conjunction with the intake manifold passage for utilizing the eductive effect of refrigerant gases flowing from the motor compartment to the intake manifold to reduce crankcase pressure. The check valves are arranged so as to permit lubricant flow from the motor compartment to the crankcase and refrigerant flow from,

the crankcase to the intake manifold, while preventing flow of lubricant from the crankcase to either the motor compartment or manifold. A relief tube extends from the check valve leading to the intake manifold and is surrounded by an eduction passage leading from the motor compartment to the intake manifold. A small bypass extends from the crankcase past the check valve to the tube entrance. The eductive effect of the refrigerant gases flowing past the mouth of the tube will thus initially reduce the crankcase pressure through the bypass, so that the check valve may then open and permit this eductive effect to continue the crankcase pressure reduction. Lubricant may thus return from the motor compartment to the crankcase.

Refer-ring more particularly to the drawing, the motorcornpressor unit is generally indicated at '11 and comprises a housing 12 having a motor compartment 13 and a crankcase 1 iseparated by a dividing wall 15. The wall has a bearing portion 16 through which a motor shaft 17 extends, this shaft being driven by the motor (not shown) and being connected to a crankshaft 18 in crankcase 14. The crankshaft has connecting rods 19 and 21 connected to pistons 22 and 23 respectively, these pistons being disposed in cylinders 24 and 25 of the compressor, which is generally indicated at 26. Cover plate 27 of the compressor has an intake manifold 28 and carries suction and discharge valves (not shown) leading to and from cylinders 24 and 25. A passage shown partially at 29 connects motor compartment 13 with intake manifold 28 through a vertical passage 31 in housing 12, so that the returning refrigerant gases may pass to the compressor. Passage 31 is of somewhat elliptical cross-sectional shape as seen in FIGURE 2 and is located above crankcase 14, the function of this passage being described below.

The lower portion of dividing wall 15 carries a check valve 32 disposed on a horizontal axis and comprising a spherical valve member 33, a seat 34 for the valve member and a passage 35 having a plurality of radial ports 36. The function of check valve 32 is to permit lubricant flow from motor compartment 1'3 to crankcase 14 but prevent reverse How. This is accomplished by providing a retaining lip 37 at the outer end of valve 32 for valve member 33, so that when the pressure in crankcase 14 is sufiiciently reduced, oil may flow through passage 35 and out through radial ports 3-5. If the pressure in crankcase 14- is higher than in motor compartment 13, valve member 33 will engage seat 34 to prevent loss of oil from the crankcase.

A horizontal wall 38 separates the upper portion of crankcase 14 from the lower end of passage 31, and a gas equalizing check valve 39 is threadably mounted in wall portion 38 and is vertically disposed below passage 31. Check valve 39 has a spherical member 41 retained in a lower position by a lip 42 on the body of valve 89, this body also having a valve seat 4-3 which member 41 will engage when forced to its upper position by excess pressure in crankcase 14. A plurality of radial ports 44 connect a passage 45 within which spherical member 41 moves and crankcase 14. Spherical member 41 is preferably of considerable weight so that if the excess pressure in crankcase 14 is relatively low, the ball will remain in its lower position permitting refrigerant gases to flow through ports 44, passage 45 and past valve seat 43 to a vertical passage 46.

Passage 46 leads to a relief tube 47 disposed within eduction passage 31. Tube 47 extends upwardly from the outlet of valve 39 and is spaced from the walls of passage 31, the mouth 48 of tube 47 being a considerable distance above the connection between passages 29 and 31, this connection being at the lower end of passage 3-1. It will thus be seen that the flow of refrigerant gases past mouth 43 of tube 47 will be substantially parallel to the erases? 3 tube as indicated by the arrows in FIGURE 1, so that a considerable eductive efiect will be created tending to draw gases upwardly through tube 47.

A relatively small bypass passage 4% may be formed in the housing of valve 39 (see FIGURE 1A), this passage extending in an inclined manner from the outer surface of the valve body to the lower end of passage 45 above valve seat 45. It will be observed that refrigerant gases Will be capable of flowing from the crankcase through bypass 12 to passage 46 even when valve member 41 engages seat 43.

In operation, assuming an initial condition in which the compressor and motor are at rest, starting of the motor will cause rotation of shaft 17 and crankshaft 18 and reciprocation of pistons 22 and 23. The pistons will draw refrigerant gases into cylinders 24 and 25 from intake manifold 12%. This will cause refrigerant gases returning to motor compartment 13 to be drawn through passageways Z9 and 31 into the intake manifold. Com pressed gases will be discharged from cylinders 24 and 25 to the condenser.

Lubricant entrained in the refrigerant gases returning to motor compartment 13 will drop to the lower portion of the compartment in readiness for return to crankcase 14 through check valve 32. Initially however, the foaming which occurs in crankcase 14 due to refrigerant mixed with the oil in the crankcase will raise the crankcase pressure, causing valve member 33 of check valve 222 to engage seat 34. Valve member 41 of check valve 39 will also engage seat 43 to prevent any slugs of oil from leaving the crankcase and entering the refrigerant system.

Meanwhile, however, gases flowing through passage 31 will flow past mouth 48 of relief tube 47 and create a reduced pressure in the relief tube due to the eductive action of the parallel flow. This will cause refrigerant gases to pass through small bypass 49 into bore and tube 47, this gas being carried into intake manifold 28. Bypass 49 is preferably small enough to prevent any appreciable quantity of lubricant from entering tube 47.

This action will quickly reduce the pressure in crankcase 14 to a point such that the weight of valve member 41 will cause it to drop against retaining lip 42 of check valve 39. This will permit a larger quantity of gases to pass through ports 44 and into bore 46 and tube 47 to be carried into intake manifold 28 by the gases flowing past mouth 43 of the relief tube.

The pressure in crankcase 14 will thus be quickly reduced to a level such that valve member 33 of check valve 32 will move away from seat 34, permitting oil to pass from the lower portion of motor compartment 13 into crankcase 14. Thus, efficient lubrication of the compressor will be maintained while at the same time the refrigerating system efficiency will be unimpaired by slugs of lubricant.

During operation, gas blowby past pistons 22 and 23 will have a tendency to maintain a slightly higher crankcase pressure than is desirable to ensure continued drain of lubricant from motor compartment 13 to crankcase 14. The novel construction including relief tube 47 and eduction passage 31 will prevent this blowby gas from creating an unduly high pressure. An eductive effect of refrigerant gases flowing past the mouth of tube 47 will serve to continually draw off excess gases in crankcase 14 through passages 44, bore 46 and tube 47, it being recalled that the weight of valve member 41 will be sufiicient to hold 'it in its lower position at low pressure differentials.

While it will be apparent that the preferred embodiment herein illustrated is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In a refrigerant motor-compressor unit of the type having an oil return check valve passage leading from the motor compartment to the compressor crankcase, a check valve disposed in said oil return check valve passage, a gas equalizing check valve passage leading from said crankcase to the compressor inlet and separated from said motor compartment, a check valve disposed in said gas equalizing check valve passage, a tube forming the exit portion of said gas equalizing check valve passage, and an unrestricted refrigerant passage leading from said motor compartment to said compressor inlet, a portion of said refrigerant passage surrounding the mouth of said tube in eductive relation therewith.

2. In a refrigerant motor-compressor unit of the type having an oil return check valve passage between the motor compartment and compressor crankcase, a gas equalizing passage leading from said crankcase to the compressor inlet and separated from said motor compartment, a check valve in said gas equalizing passage movable between a closed position preventing flow from the crankcase to the compressor inlet and an open position permitting said flow, a relief tube forming the exit portion of said gas equalizing passage, a restricted passage leading from the crankcase to the entrance of said tube and bypassing said check valve, and an unrestricted refrigerant return passage leading from said motor compartment to said compressor inlet, said last mentioned passage having a portion in eductive relation with the exit of the said tube.

3. In a refrigerant motor-compressor unit, a motor compartment, a compressor having a crankcase and a cylinder inlet, an oil return passage leading from the lower portion of said motor compartment to said crankcase, an oil return check valve in said passage movable from an open position to a closed position preventing oil flow from the crankcase to the motor compartment in response to a pressure differential in the crankcase, a gas equalizing passage leading from the upper portion of said crankcase to the compressor inlet and separated from said motor compartment, a gas equalizing check valve in said gas equalizing passage movable between an open position and a position preventing fluid flow from the crankcase to the compressor inlet, means urging said gas equalizing check valve to its open position with a relatively light force, the gas equalizing check valve being responsive to a substantial pressure rise in said crankcase to move to its closed position, and a refrigerant return passage separated along its main extent from said gas equalizing passage leading from said motor compartment to said compressor inlet and having a portion in eductive relation with said gas equalizing passage.

4. In a refrigerant motor-compressor unit, a motor compartment, a compressor having a crankcase and a cylinder inlet, an oil return passage leading from the lower portion of said motor compartment to said crankcase, an oil return check valve in said passage movable between an open position and a closed position preventing oil flow from the crankcase to the motor compartment, a gas equalizing passage leading from the upper portion of said crankcase to the compressor inlet and separated from said motor compartment, a gas equalizing check valve in said gas equalizing passage movable between an open position and a position preventing fiuid flow from the crankcase to the compressor inlet, means urging said gas equalizing check valve to its open position with a relatively light force, the gas equalizing check valve being responsive to a substantial pressure rise in said crankcase to move to its closed position, a tube forming the exit portion of said gas equalizing passage, a refrigerant return passage separated along its main extent from said gas equalizing passage leading from said motor compartment to said compressor inlet, and a portion of said refrigerant return passage extending parallel to and surrounding said tube whereby an eductive effect at the tube mouth will be created.

-5. In a refrigerant motor-compressor unit of the type having an oil return check valve passage between the motor compartment and crankcase, a gas equalizing check valve passage between the crankcase and compressor inlet and separated from said motor compartment, an unrestricted refrigerant return passage leading from the motor compartment to the compressor inlet, said refrigerant return passage having a straight portion adjacent the compressor inlet, a check valve in said gas equalizing check valve passage, a tube disposed within the straight portion of said refrigerant return passage and forming the exit portion of said gas equalizing check valve passage, and a restricted passage bypassing said gas equalizing check valve and leading from said crankcase to the inner portion of said tube.

6. In a compressor for a volatile fluid having lubricating oil entrained therein, a compressor inlet, a crankcase, an oil separating chamber, an oil return passage leading from said oil separating chamber to said crankcase, a gas equalizing check valve passage leading from said crankcase to said compressor inlet and separated from said chamber, a check valve in said gas equalizing check valve passage, a gas supply passage separated along its main extent from said gas equalizing passage leading to said compressor inlet, and means forming parts of said gas supply passage and said check valve passage for causing eduction of gas from said crankcase to said inlet in response to gas flow through said gas supply passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,649,584 Greenwald Nov. 15, 1927 1,948,572 Floyd Feb. 27, 1934 2,048,025 Philipp July 21, 1936 2,074,323 Borgerd Mar. 23, 1937 2,150,487 Brown Mar. 14, 1939 2,233,168 Johnson Feb. 25, 1941 2,306,813 King Dec. 29, 1942 2,673,026 Gerteis Mar. 23, 1954 2,719,408 Penn Oct. 4, 1955 2,741,424 Ploeger Apr. 10, 1956 2,926,840 Soumerai Mar. 1, 1960 2,963,218 Tower Dec. 6, 1960 FOREIGN PATENTS 407,837 France Oct. 13, 1909 715,957 France Apr. 24, 1931 

1. IN A REFRIGERANT MOTOR-COMPRESSOR UNIT OF THE TYPE HAVING AN OIL RETURN CHECK VALVE PASSAGE LEADING FROM THE MOTOR COMPARTMENT TO THE COMPRESSOR CRANKCASE, A CHECK VALVE DISPOSED IN SAID OIL RETURN CHECK VALVE PASSAGE, A GAS EQUALIZING CHECK VALVE PASSAGE LEADING FROM SAID CRANKCASE TO THE COMPRESSOR INLET AND SEPARATED FROM SAID MOTOR COMPARTMENT, A CHECK VALVE DISPOSED IN SAID GAS EQUALIZING CHECK VALVE PASSAGE, A TUBE FORMING THE EXIT PORTION OF SAID GAS EQUALIZING CHECK VALVE PASSAGE, AND AN UNRESTRICTED REFRIGERANT PASSAGE LEADING FROM SAID MOTOR COMPARTMENT TO SAID COMPRESSOR INLET, A PORTION OF SAID REFRIGERANT PASSAGE SURROUNDING THE MOUTH OF SAID TUBE IN EDUCTIVE RELATION THEREWITH. 